# Scheduled Reports

## Objective

Deliver a saved report on a schedule instead of making people rebuild it weekly.

Recurring rendering and delivery of a saved analytics report to a chosen set of recipients.

## Before You Begin

This feature is being added to an application that already exists and already
works. Do not scaffold a new project, and do not assume a blank slate.

Inspect the codebase first and establish:

- The existing application structure and where code of this kind already lives.
- The framework and version in use.
- The existing design system — colours, spacing, typography, and component conventions.
- Existing UI components you can reuse instead of writing new ones.
- The existing database structure, if this feature needs to persist anything.
- The existing authentication and authorization system, if this feature is user-scoped.
- Dependencies already installed, so you don't add a library that duplicates one.
- The existing test setup and conventions.

Only start writing code once you understand the above. If the application
already implements part of this feature, extend it rather than replacing it.

## Implementation Instructions

1. Let a user attach a schedule to a saved report: frequency, send time, and the time zone the schedule runs in.
2. Render each send with the filters, date range, and time zone the report author selected — not the recipient's or the server's.
3. Re-check every recipient's access to the report AT SEND TIME. Permission granted three months ago is not permission today.
4. Record each send as a run with a status, so a failure is visible rather than a report that quietly stopped arriving.
5. Do NOT build batching cadence, per-user notification preferences, or urgent-versus-digestible classification here. Those are owned by Notification Digests; route delivery through it.

## UI and UX Requirements

Match the application's existing design system exactly. Reuse its components,
spacing, and typography. This feature should look like it was always there.

## Responsive Requirements

Works on mobile, tablet, and desktop. Touch targets are large enough to hit on a
phone, and nothing overflows horizontally at 320px.

## Accessibility Requirements

- Fully keyboard navigable.
- Correct semantic elements and ARIA roles.
- Visible focus states.
- Meets WCAG AA contrast.
- Dynamic changes are announced to screen readers.
- Respects prefers-reduced-motion.

## Edge Cases

- A recipient who lost access must be dropped from that send and the owner told — not sent a report they can no longer open.
- A report with no rows should be skipped or labelled as empty by an explicit setting. Silently sending a blank table trains people to ignore it.
- Two schedules on the same report at the same time must not produce two sends. Deduplicate on report, window, and recipient.
- Daylight saving shifts the wall-clock send time. Pick whether the schedule follows local time or fixed UTC and hold to it.
- A failed render must retry with a bounded backoff, then stop and alert the owner. Infinite retries send twelve copies at 3am.
- A worker restart mid-run must not resend an already-delivered report — mark delivery, not just attempt.

## Testing

Exercise the feature end to end in the running application. Cover every edge case
above, then run the existing test suite and confirm nothing regressed.

## Acceptance Criteria

- [ ] A saved report can be scheduled with a frequency, send time, and time zone.
- [ ] Each send reproduces the author's filters, range, and time zone exactly.
- [ ] Recipient access is re-evaluated at send time and revoked recipients are excluded.
- [ ] Empty reports follow an explicit skip-or-send setting.
- [ ] Duplicate schedules and worker retries never produce a duplicate delivery.
- [ ] Send history with success and failure status is visible to the report owner.
- [ ] The feature matches the existing design system.
- [ ] No existing functionality is broken.

## Adaptation Rules

- Match the existing design system. Do not introduce a new colour palette,
  spacing scale, or component library.
- Reuse existing components and utilities wherever they fit.
- Follow the naming, file layout, and code style already present.
- Do not upgrade, replace, or remove existing dependencies to make this
  feature fit. Adapt the feature to the app, not the app to the feature.
- Do not break existing functionality. If a change is genuinely required in
  existing code, make the smallest one that works and say so.
- If something in these instructions conflicts with how the application is
  built, follow the application and explain the deviation.

## Final Verification

Before you report the work as done:

1. Re-read the acceptance criteria above and check each one against what you
   actually built.
2. Run the application and exercise the feature end to end.
3. Run the existing test suite and confirm you have broken nothing.
4. Check the feature on mobile, tablet, and desktop widths.
5. Check keyboard navigation and focus handling.
6. Summarize what changed: files added, files modified, and anything you
   deliberately did differently because of how this application is built.

If any acceptance criterion is unmet, fix it before reporting completion.